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WO2015025663A1 - Negative electrode, electricity storage device and vehicle - Google Patents

Negative electrode, electricity storage device and vehicle Download PDF

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Publication number
WO2015025663A1
WO2015025663A1 PCT/JP2014/069279 JP2014069279W WO2015025663A1 WO 2015025663 A1 WO2015025663 A1 WO 2015025663A1 JP 2014069279 W JP2014069279 W JP 2014069279W WO 2015025663 A1 WO2015025663 A1 WO 2015025663A1
Authority
WO
WIPO (PCT)
Prior art keywords
active material
material particles
metal foil
negative electrode
particle diameter
Prior art date
Application number
PCT/JP2014/069279
Other languages
French (fr)
Japanese (ja)
Inventor
雄一 平川
雅巳 冨岡
木下　恭一
Original Assignee
株式会社 豊田自動織機
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 株式会社 豊田自動織機 filed Critical 株式会社 豊田自動織機
Publication of WO2015025663A1 publication Critical patent/WO2015025663A1/en

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
    • H01G11/22—Electrodes
    • H01G11/26—Electrodes characterised by their structure, e.g. multi-layered, porosity or surface features
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
    • H01G11/22—Electrodes
    • H01G11/24—Electrodes characterised by structural features of the materials making up or comprised in the electrodes, e.g. form, surface area or porosity; characterised by the structural features of powders or particles used therefor
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
    • H01G11/66—Current collectors
    • H01G11/70—Current collectors characterised by their structure
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/64—Carriers or collectors
    • H01M4/66—Selection of materials
    • H01M4/661—Metal or alloys, e.g. alloy coatings
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/64—Carriers or collectors
    • H01M4/70—Carriers or collectors characterised by shape or form
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/60—Other road transportation technologies with climate change mitigation effect
    • Y02T10/70—Energy storage systems for electromobility, e.g. batteries

Definitions

  • the present invention relates to a negative electrode, a power storage device including the negative electrode, and a vehicle equipped with the power storage device.
  • power storage devices such as lithium ion secondary batteries and nickel metal hydride secondary batteries are well known as power storage devices mounted on vehicles, for example.
  • an electrode assembly configured by laminating or winding two types of electrode sheets is accommodated in a case.
  • Each electrode sheet includes a metal foil, and the metal foil has an active material layer on the surface thereof.
  • the active material layer includes active material particles.
  • Patent Document 1 a battery with improved peel strength (adhesion strength) of the active material layer to the metal foil has been proposed.
  • a paste containing active material particles active material mixture
  • the drying process high-temperature vapor of the solvent is supplied to promote melting of the binder contained in the paste.
  • the peeling strength is improved by strengthening the binding between the active material layer and the metal foil by the binder.
  • a power storage device such as a secondary battery is repeatedly applied with vibration by being mounted on a vehicle or the active material layer is repeatedly expanded and contracted with charge / discharge. May peel from the metal foil.
  • the active material layer When the active material layer is peeled from the metal foil, it may cause a decrease in the performance as a power storage device such as a decrease in electric capacity, and further suppress the peeling of the active material layer from the metal foil. Is expected.
  • An object of the present invention is to provide a negative electrode, a power storage device, and a vehicle that can prevent an active material layer from peeling from a metal foil.
  • a first aspect for achieving the above object provides a negative electrode including a metal foil and an active material layer including a plurality of negative electrode active material particles having a predetermined average particle diameter on the surface of the metal foil.
  • the surface of the metal foil includes a formation region where the active material layer is located. In the formation region, the metal foil has a recess on its surface, and some of the active material particles of the active material particles are active material particles that are at least partially present in the recess. Of the active material particles present at least partially in the recess, the average distance between the centers of adjacent active material particles is 70% or more and 98% or less of the average particle diameter.
  • the second aspect provides a negative electrode including a metal foil and an active material layer including a plurality of negative electrode active material particles having a predetermined average particle diameter on the surface of the metal foil.
  • the surface of the metal foil includes a formation region where the active material layer is located. Some of the active material particles are active material particles that are at least partially embedded in the formation region. Of the active material particles that are at least partially embedded in the formation region, the average distance between the centers of two adjacent active material particles is 70% or more and 98% or less of the average particle diameter.
  • a power storage device including an electrode assembly having a layered structure.
  • the electrode includes the negative electrode of the first aspect or the second aspect.
  • the perspective view which shows a secondary battery typically.
  • the schematic diagram which shows the state which observed the cross section of the negative electrode sheet with the scanning electron microscope.
  • the graph which shows the relationship between the distance between average particle
  • the graph which shows the relationship between the distance between average particle
  • the secondary battery 10 as a power storage device is mounted on a vehicle such as an industrial vehicle or a passenger vehicle.
  • the secondary battery 10 includes a case 11 having a substantially rectangular parallelepiped shape as a whole.
  • the case 11 has a bottomed cylindrical main body member 12 and a flat lid member 13 that seals the opening 12 a of the main body member 12.
  • Both the main body member 12 and the lid member 13 are made of metal such as stainless steel or aluminum.
  • a positive electrode terminal 15 and a negative electrode terminal 16 are fixed to the lid member 13 and extend outward.
  • the case 11 is filled with an electrolyte according to the type of the secondary battery 10 such as a lithium ion secondary battery or a nickel hydride secondary battery.
  • an electrolytic solution for example, one or more nonaqueous electrolytic solutions selected from propylene carbonate (PC), ethylene carbonate (EC), and dimethyl carbonate (DMC) can be used.
  • PC propylene carbonate
  • EC ethylene carbonate
  • DMC dimethyl carbonate
  • an alkali metal salt that is soluble in an organic solvent such as LiPF 6 , LiBF 4 , and LiAsF 6 can be used.
  • the case 11 houses an electrode assembly 25 covered with an insulating bag (not shown).
  • the electrode assembly 25 includes a positive electrode sheet 21 as a positive electrode, a negative electrode sheet 22 as a negative electrode, and a separator 23 that insulates between the positive electrode sheet 21 and the negative electrode sheet 22.
  • the electrode assembly 25 is a stacked electrode assembly in which the positive electrode sheet 21 and the negative electrode sheet 22 are stacked so as to alternately overlap each other with a separator 23 interposed therebetween.
  • the separator 23 is made of an insulating resin material such as polyethylene or polypropylene, and is a rectangular porous sheet having a fine pore structure.
  • each of the positive electrode sheet 21 and the negative electrode sheet 22 includes a rectangular sheet-like metal foil 26.
  • the thickness of the metal foil 26 is, for example, 10 ⁇ m or more and 50 ⁇ m or less, and preferably 15 ⁇ m or more and 25 ⁇ m or less.
  • the metal foil 26 is made of metal according to the type of the secondary battery 10 such as a lithium ion secondary battery or a nickel hydride secondary battery.
  • the metal used for the metal foil 26 differs depending on the positive electrode sheet 21 and the negative electrode sheet 22.
  • the metal foil 26 of the positive electrode sheet 21 is made of aluminum
  • the metal foil 26 of the negative electrode sheet 22 is made of copper.
  • an active material layer 27 is provided on the entire surface except for the non-formation region 26b extending along the edge 26a of each metal foil 26.
  • the non-formation region 26b is a region where the active material layer 27 is not formed.
  • the active material layer 27 will be described in detail later.
  • the positive electrode current collection tab 21a which is a part of the non-formation area
  • the negative electrode current collection tab 22a which is a part of the non-formation area
  • a positive electrode current collecting tab group 28 is provided on the edge 25a of the electrode assembly 25 so as to extend upward.
  • the positive electrode current collecting tab group 28 includes a plurality of positive electrode current collecting tabs 21a stacked in layers.
  • a negative electrode current collecting tab group 29 is provided on the edge 25 a of the electrode assembly 25 at a portion different from the positive electrode current collecting tab group 28 so as to extend upward.
  • the negative electrode current collecting tab group 29 includes a plurality of negative electrode current collecting tabs 22a stacked in layers.
  • the positive electrode current collecting tab group 28 (positive electrode current collecting tab 21a) is electrically connected to the positive electrode terminal 15 described above.
  • the negative electrode current collecting tab group 29 (negative electrode current collecting tab 22 a) is electrically connected to the negative electrode terminal 16.
  • the active material layer 27 includes active material particles, a binder, and a conductive agent (conductive aid).
  • the conductive agent is dispersed in the binder.
  • the active material for positive electrodes used for the active material layer 27 of the positive electrode sheet 21 is, for example, LiCoO 2 , Li 2 MnO 2 , and LiNi 1/3 Mn 1/3 Co 1/3 O 2 .
  • the binder used for the active material layer 27 of the positive electrode sheet 21 is, for example, polyvinylidene fluoride (PVDF) or polytetrafluoroethylene (PTFE).
  • the conductive agent used for the active material layer 27 of the positive electrode sheet 21 is, for example, acetylene black (AB) or ketjen black (registered trademark) (KB).
  • the active material for a negative electrode used for the active material layer 27 of the negative electrode sheet 22 is, for example, silicon oxide represented by a composition formula of SiO n (0.1 ⁇ n ⁇ 2), such as SiO 2 (silicon dioxide), SiO 2 (Silicon monoxide).
  • the binder used for the active material layer 27 of the negative electrode sheet 22 is, for example, PVDF or PTFE.
  • the electrically conductive agent used for the active material layer 27 of the negative electrode sheet 22 is AB or KB, for example.
  • the active material layer 27 of the negative electrode sheet 22 will be described in detail with reference to FIG.
  • the active material particles 27a are bound to each other by a binder 27b.
  • the average particle diameter of the active material particles 27a is, for example, 2 ⁇ m or more and 10 ⁇ m or less, and preferably 4 ⁇ m or more and 8 ⁇ m or less.
  • the “average particle size” in this specification means the particle size at an integrated value of 50% in the particle size distribution obtained by the laser diffraction / scattering method.
  • each “particle diameter” in the active material particles 27a means a particle diameter observed with a scanning electron microscope (SEM).
  • the active material particles 27a are present in the recesses 26d of the surface 26c of the metal foil 26. That is, in the formation region 27c of the active material layer 27, a part of the particles of the active material particles 27a adjacent to the surface 26c of the metal foil 26 is buried so as to exist in the recess 26d of the surface 26c. In other words, the active material particles 27a are at least partially embedded, that is, embedded in the surface portion of the metal foil 26 including the surface 26c. A portion of the active material particles 27 a excluding the buried active material particles 27 a is located above the surface 26 c of the metal foil 26. The surfaces of the active material particles 27a that are embedded in the metal foil 26 are in contact with or close to the surfaces that define the recesses 26d, for example, the side surfaces and the bottom surface.
  • the average of the distances L from the center C1 to the center C2 of the adjacent active material particles 27a is the active material particle 27a.
  • the distance is preferably 70% to 98%, more preferably 72% to 95%.
  • the ratio of the average of the distance L from the center C1 to the center C2 (average distance between centers) with respect to the average particle diameter is simply defined as “average interparticle distance”.
  • the center of the active material particle 27a means a direction along the surface direction of the metal foil 26 and a direction orthogonal to the surface direction of the metal foil 26 when observed with a scanning electron microscope. Means the center of
  • the density (electrode density) of the negative electrode sheet 22 is, for example, 1.07 g / cm 3 when the average interparticle distance is 98%, and is, for example, 1.08 g / cm 3 when the average interparticle distance is 70%.
  • the density of the negative electrode sheet 22 is, for example, 1.25 g / cm 3 when the average interparticle distance is 72%, and is, for example, 1.09 g / cm 3 when the average interparticle distance is 95%.
  • the active material particles 27 a In the active material layer 27 of the negative electrode sheet 22, among the active material particles 27 a partially present in the recesses 26 d of the surface 26 c of the metal foil 26, the active material particles 27 a having a particle diameter equal to or larger than the average particle diameter.
  • the active material particles 27a are not recessed into the surface 26 c of the metal foil 26 in the formation region 27 c of the active material layer 27.
  • a preparation step is performed in which active material particles 27a, a conductive agent, a binder 27b, and a solvent such as N-methylpyrrolidone (NMP) are mixed to obtain a paste-like active material mixture.
  • NMP N-methylpyrrolidone
  • the paste-like active material mixture obtained in the preparation step is applied to the surface (both sides) 26c of the strip-like (long sheet-like) metal foil 26 obtained in a step different from the preparation step.
  • a coating process is performed in which the active material layer 27 is formed by coating with a uniform thickness.
  • the uniform thickness is, for example, 70 ⁇ m or more and 80 ⁇ m or less including a copper foil having a thickness of 18 ⁇ m. Further, in the coating step, a non-formation region 26b is formed on one side (edge) in the width direction of the metal foil 26 where the active material mixture is not coated with a constant width over the entire length direction.
  • a drying step is performed in which the metal foil 26 on which the active material layer 27 is formed is passed through a dryer (drying furnace) to remove the solvent contained in the active material layer 27.
  • a pressing process is performed in which the active material layer 27 is compressed and densified and smoothed.
  • the roll press machine passes the metal foil 26 having the active material layer 27 formed on the surface 26c through a gap formed between a pair of cylindrical rollers arranged in parallel to each other, thereby causing the active material layer 27 to pass through. Compress, ie press.
  • the active material particles 27 a included in the active material layer 27 do not sink into the surface 26 c of the metal foil 26 due to the linear pressure applied between the rollers of the roll press machine. This is done by setting the linear pressure. Through this pressing step, a belt-like (long sheet-like) positive electrode sheet 21 is obtained.
  • the active material particles 27a included in the active material layer 27 are applied to the surface 26c ( This is performed by setting the linear pressure to be embedded in the surface portion.
  • the average particle distance is a line that is preferably 70% to 98%, more preferably 72% to 95% of the average particle diameter of the active material particles 27a included in the active material layer 27. Set to pressure.
  • the particle diameter of the active material particles 27 a partially present in the recesses 26 d of the surface 26 c of the metal foil 26 is equal to or greater than the average particle diameter.
  • the active material particles 27a are set to a linear pressure that sinks into the metal foil 26 to a depth of 50% or less of the particle diameter of the active material particles 27a. That is, the active material particles 27a of the negative electrode sheet 22 are pressed with a linear pressure larger than the linear pressure applied to the positive electrode active material particles 27a, thereby forming the concave portions 26d on the surface of the metal foil 26. , So as to partially exist in the recess 26d. Through this pressing step, a strip-like (long sheet-like) negative electrode sheet 22 is obtained.
  • the substantially rectangular positive electrode sheet 21 and the negative electrode sheet 22 are formed by stamping the belt-like (long sheet-like) positive electrode sheet 21 and the negative electrode sheet 22 respectively.
  • the electrode assembly 25 is formed by laminating the positive electrode sheet 21 and the negative electrode sheet 22 with the separator 23 interposed therebetween. Thereby, the electrode assembly 25 is completed.
  • the positive electrode terminal 15 is joined and electrically connected to the positive electrode current collecting tab group 28 (positive electrode current collecting tab 21a) of the electrode assembly 25.
  • the negative electrode current collecting tab group 29 (the negative electrode current collecting tab 22a) is joined and electrically connected to the negative electrode terminal 16.
  • the electrode assembly 25 is housed in the main body member 12 while being covered with the insulating bag.
  • a lid member 13 is assembled to the main body member 12 with the positive electrode terminal 15 and the negative electrode terminal 16 protruding from the upper surface.
  • an electrolyte electrolytic solution
  • the compounding ratio of the active material particles, KB, and binder (solid content) was 80.75: 4.25: 15 in terms of mass ratio.
  • the obtained paste-like active material mixture is applied to the surface (both sides) of the strip-shaped copper foil and molded.
  • the basis weight of the active material mixture was 7 mg / cm 2 .
  • the thickness including the active material mixture and the copper foil having a thickness of 18 ⁇ m is 76 ⁇ m.
  • the copper foil coated with the active material mixture is passed through a dryer to remove the solvent and dry.
  • the dried active material layer is compressed by passing the dried copper foil through a roll press. And the thickness of the active material layer became 15 micrometers.
  • negative electrode sheets with different average inter-particle distances were obtained by adjusting the linear pressure applied between the rollers of the roll press machine. (Observation with a scanning electron microscope)
  • the inventors cut the obtained negative electrode sheet with a focused ion beam processing observation apparatus (JEM-9310FIB, manufactured by JEOL Ltd.), and a cross-section of the cross section with a scanning electron microscope (S-4800, manufactured by Hitachi High-Technologies Corporation). Was observed.
  • the active material particles embedded in the surface of the copper foil the active material particles having a diameter larger than the average particle diameter are embedded in the copper foil to a depth of 50% or less of the particle diameter of the active material particles. That is, for the sample present in the concave portion of the copper foil, no wrinkles or cracks occurred in the copper foil at the boundary portion.
  • the active material particles embedded in the surface of the copper foil the active material particles having a diameter equal to or larger than the average particle diameter are embedded in the copper foil to a depth exceeding 50% of the particle diameter of the active material particles.
  • the sample which is creased, the wrinkles etc. had arisen in the copper foil in the said boundary part.
  • the active material particles embedded in the surface of the copper foil in the active material layer of the negative electrode sheet the active material particles having a diameter equal to or larger than the average particle diameter exceed 50% of the particle diameter of the active material particles. It has been confirmed that it is preferable to squeeze into the copper foil to a depth that does not. (Measurement of peel strength) Peel strength was measured using an adhesive tape and adhesive sheet test method. First, each of the manufactured strip-shaped negative electrode sheets was punched to prepare strip-shaped samples each having a length of 80 mm and a width of 25 mm.
  • a commercially available strong double-sided tape (manufactured by 3M, YHB Y-4945) is used on a rectangular test table supported so as to be slidable.
  • the sample can be affixed in the state in which it is left.
  • the end of the sample in the longitudinal direction is fixed to a fixture that is supported so as to be movable in a direction orthogonal to the sample attachment surface on the test table.
  • the load measuring device manufactured by Minebea Co., Ltd., LTS-200N-S20
  • the load measuring device is moved at a constant speed of 20 mm / min in a direction away from the sample, and the sample is peeled off from the test table
  • the load was measured.
  • the average value of the loads per 1 cm width between 10 mm and 30 mm from the position where peeling was started was measured as the peeling strength.
  • the peel strength between the active material layer and the copper foil is obtained by the anchor effect of the active material particles to the copper foil in addition to the adhesion by the binder. It was confirmed that can be suitably improved.
  • the average interparticle distance is 75% or more and a peel strength of 2.67 N / cm is secured.
  • the counter electrode was punched into a circle with a diameter of 13 mm
  • the evaluation electrode was punched into a circle with a diameter of 11 mm
  • a separator Hoechst Celanese glass filter and celgard 2400
  • This electrode assembly was accommodated in a battery case (manufactured by Hosen Co., Ltd., CR2032 coin cell).
  • a non-aqueous electrolyte in which LiPF 6 was dissolved at a concentration of 1 M (mol) in a mixed solvent in which ethylene carbonate and diethyl carbonate were mixed at a volume ratio of 1: 1 was injected into the battery case.
  • the discharge capacity retention ratio is a value obtained by dividing the N-th cycle discharge capacity by the initial discharge capacity ((N-cycle discharge capacity) / (first-cycle discharge capacity) ⁇ 100). (N is an integer value).
  • FIG. 5 shows the results of measuring the number of cycles until the discharge capacity retention rate reaches 80% for each sample of a lithium ion secondary battery manufactured using negative electrode sheets with different average interparticle distances.
  • the active material particles partially present in the recesses interfere with each other due to the expansion of the active material particles accompanying charging, and stress is generated. It is considered that the cycle characteristics deteriorate due to the layer peeling from the copper foil.
  • the separation distance between the active material particles partially existing in the recess is larger than when the average interparticle distance is 98% or less. That is, the number of active material particles partially present in the recess is small. Therefore, it is considered that the active material layer is easily peeled off from the copper foil with charge / discharge, and the cycle characteristics are deteriorated due to this.
  • the average interparticle distance in the positive electrode sheet is preferably 70% or more.
  • the active material layer 27 is made of metal by the anchor effect of the active material particles 27 a with respect to the metal foil 26. Separation from the foil 26 can be suppressed. And among the active material particles 27a partially existing in the recess 26d, when the average inter-particle distance between two adjacent active material particles 27a is 70% or more, it is compared with the case where it is less than 70%. And it can suppress that active material particle
  • the average interparticle distance of the active material particles 27a is 98% or less, compared with the case where it exceeds 98%, the distance between the active material particles 27a is reduced to enhance the anchor effect, thereby charging and discharging. Accordingly, the active material layer 27 can be prevented from peeling from the metal foil 26. Therefore, it can suppress that the active material layer 27 and the metal foil 26 peel.
  • the active material layer 27 can be prevented from peeling from the copper metal foil 26.
  • the positive electrode sheet 21 and the negative electrode sheet 22 are laminated with the separator 23 interposed therebetween, and the positive electrode sheet 21 and the negative electrode sheet 22 are layered. For this reason, in the electrode assembly 25 in which the positive electrode sheet 21 and the negative electrode sheet 22 have a layered structure, it is possible to suppress the active material layer 27 from being separated from the metal foil 26 of the negative electrode sheet 22.
  • the average inter-particle distance between the adjacent active material particles 27a is set to 72% or more to further increase the secondary battery.
  • the cycle characteristic as 10 can be improved.
  • the average inter-particle distance between the adjacent active material particles 27a is set to 95% or less to further increase the secondary battery.
  • the cycle characteristic as 10 can be improved.
  • the average inter-particle distance between adjacent active material particles 27a is 75% or more, so that the active material layer 27 It is possible to prevent the time required for impregnating the electrolyte (electrolyte solution) into a long time.
  • the average inter-particle distance between the adjacent active material particles 27a is set to 75% or more, so that the secondary battery 10 Is mounted on an industrial vehicle, it is possible to suppress the active material layer 27 from being peeled off from the metal foil 26 even under a condition in which large vibrations are applied to the secondary battery 10.
  • the embodiment is not limited as described above, and may be embodied as follows, for example.
  • the auxiliary metal foil 35 which is the same metal as the metal foil 26, is joined to the non-formation region 26 b where the active material layer 27 is not formed on the surface 26 c of the metal foil 26 in the negative electrode sheet 22. It may be.
  • the metal foil 26 and the auxiliary metal foil 35 may be joined by, for example, seam welding, which is a type of resistance welding.
  • the thickness of the auxiliary metal foil 35 is preferably set to be substantially the same as that of the active material layer 27.
  • the depression 26d is formed by pressurizing the formation region 27c of the active material layer 27 by, for example, pressing.
  • the auxiliary metal foil 35 and the metal foil 26 sandwich a sheet 35 a made of a metal having higher electrical resistance than the metal forming the auxiliary metal foil 35 and the metal foil 26. It may be joined in a state. According to this, resistance welding of the auxiliary metal foil 35 and the metal foil 26 can be facilitated.
  • the active material layer 27 may be formed only on one side of the metal foil 26.
  • the electrode assembly 25 may have a positive electrode sheet 21, a negative electrode sheet 22, and a separator 23 in a strip shape (long sheet shape).
  • the positive electrode sheet 21 and the negative electrode sheet 22 are wound in a spiral shape with the separator 23 sandwiched therebetween, and the electrode assembly 25 is formed so that the positive electrode sheet 21 and the negative electrode sheet 22 form a layered structure (laminated structure). May be.
  • a non-formation region 26b extending along the length direction of the positive electrode sheet 21 is formed at one edge (left edge in FIG. 7) in the width direction (lateral direction).
  • the formation region 26b becomes the positive electrode current collecting tab 21a.
  • a non-formation region 26 b extending along the length direction of the negative electrode sheet 22 is formed on the other edge portion in the width direction (the right edge portion in FIG. 7).
  • 26b becomes the negative electrode current collection tab 22a.
  • the positive electrode current collecting tab group 28 in which the positive electrode current collecting tab 21 a has a layered structure is provided on the left edge portion of the electrode assembly 25.
  • a negative electrode current collecting tab group 29 in which the negative electrode current collecting tab 22a has a layered structure may be provided on the right edge of the solid body 25.
  • the shape of the positive electrode sheet 21 and the negative electrode sheet 22 may be changed.
  • the active material particles 27 a may exist by being partially embedded in the recesses 26 d of the metal foil 26.
  • the electrode assembly 25 may be laminated by folding the positive electrode sheet 21 and the negative electrode sheet 22 into a bellows shape with the separator 23 interposed therebetween.
  • the metal foil 26 used for the positive electrode sheet 21 may be formed from different metals, such as nickel and stainless steel.
  • the metal of the metal foil 26 may be changed.
  • the active material particles 27a existing in the recesses 26d on the surface 26c of the metal foil 26 are 50% or more of the particle diameter of the active material particles 27a. It may exist in the recess 26d to the depth, that is, it may be embedded in the metal foil 26. However, from the viewpoint of suppressing generation of wrinkles of the metal foil 26, it is preferable to configure as in the above embodiment.
  • the number of the positive electrode sheet 21 and the negative electrode sheet 22 constituting the electrode assembly 25 may be appropriately changed.
  • the electrode assembly 25 may include one positive electrode sheet 21 and one negative electrode sheet 22.
  • the shape of the case 11 may be a columnar shape or an elliptical column shape that is flat in the horizontal direction.
  • a compressor for an air conditioner is supplied by electric power supplied from the secondary battery 10
  • an electric motor for driving the wheels or an electrical component such as a car navigation system may be driven. According to this, it can suppress that the active material layer 27 peels from the metal foil 26, and can improve the durability as the secondary battery 10. Therefore, it can suppress that the replacement cycle of the secondary battery 10 becomes short in a vehicle.
  • the present invention may be embodied in an electric double layer capacitor as a power storage device.

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Abstract

The purpose of the present invention is to provide: a negative electrode wherein separation of an active material layer from a metal foil can be suppressed; an electricity storage device; and a vehicle. A negative electrode according to the present invention is provided with: a metal foil; and an active material layer which is on the surface of the metal foil and contains a plurality of active material particles for negative electrodes, said active material particles having a predetermined average particle diameter. The surface of the metal foil has a formation region on which the active material layer is positioned. The surface of the metal foil has a recessed portion in the formation region. Some of the active material particles are at least partially present in the recessed portion. The average distance between the centers of two adjacent active material particles, which are at least partially present in the recessed portion, is from 70% to 98% (inclusive) of the average particle diameter of the active material particles.

Description

負極電極、蓄電装置、及び車両Negative electrode, power storage device, and vehicle
　本発明は、負極電極、負極電極を含む蓄電装置、及び蓄電装置を搭載した車両に関する。 The present invention relates to a negative electrode, a power storage device including the negative electrode, and a vehicle equipped with the power storage device.
　従来から、例えば車両に搭載される蓄電装置として、リチウムイオン二次電池やニッケル水素二次電池などの蓄電装置がよく知られている。例えば、リチウムイオン二次電池では、二種類の電極シートを積層、或いは捲回して構成された電極組立体がケースに収容されている。各電極シートは金属箔を含み、金属箔はその表面に活物質層を有する。活物質層は、活物質粒子を含む。 Conventionally, power storage devices such as lithium ion secondary batteries and nickel metal hydride secondary batteries are well known as power storage devices mounted on vehicles, for example. For example, in a lithium ion secondary battery, an electrode assembly configured by laminating or winding two types of electrode sheets is accommodated in a case. Each electrode sheet includes a metal foil, and the metal foil has an active material layer on the surface thereof. The active material layer includes active material particles.
　このようなリチウムイオン二次電池の中には、特許文献１に記載されるように、金属箔に対する活物質層の剥離強度（密着強度）を高めたものが提案されている。該二次電池では、活物質粒子を含むペースト（活物質合剤）を金属箔に塗布して乾燥させた後に、乾燥したペーストに対してプレス加工が施される。特許文献１の製造方法では、乾燥工程において、溶媒の高温蒸気を供給してペーストに含まれるバインダの溶融が促進される。これによりバインダによる活物質層と金属箔との間の結着を強固にすることにより剥離強度を向上させている。 Among such lithium ion secondary batteries, as described in Patent Document 1, a battery with improved peel strength (adhesion strength) of the active material layer to the metal foil has been proposed. In the secondary battery, a paste containing active material particles (active material mixture) is applied to a metal foil and dried, and then the dried paste is pressed. In the manufacturing method of Patent Document 1, in the drying process, high-temperature vapor of the solvent is supplied to promote melting of the binder contained in the paste. Thereby, the peeling strength is improved by strengthening the binding between the active material layer and the metal foil by the binder.
特開２００８－１０３０９８号公報JP 2008-103098 A
　ところで二次電池などの蓄電装置は、車両に搭載されるなどして振動が繰り返し与えられたり、充放電に伴って活物質層が繰り返し膨張及び収縮したりすることに起因して、活物質層が金属箔から剥離する虞がある。活物質層が金属箔から剥離した場合には、電気容量が低下するなど、蓄電装置としての性能が低下する原因になる場合があり、活物質層が金属箔から剥離することをさらに抑制することが期待されている。 By the way, a power storage device such as a secondary battery is repeatedly applied with vibration by being mounted on a vehicle or the active material layer is repeatedly expanded and contracted with charge / discharge. May peel from the metal foil. When the active material layer is peeled from the metal foil, it may cause a decrease in the performance as a power storage device such as a decrease in electric capacity, and further suppress the peeling of the active material layer from the metal foil. Is expected.
　本発明の目的は、活物質層が金属箔から剥離することを抑制できる負極電極、蓄電装置、及び車両を提供することにある。 An object of the present invention is to provide a negative electrode, a power storage device, and a vehicle that can prevent an active material layer from peeling from a metal foil.
　上記目的を達成する第１の態様は、金属箔と、前記金属箔の表面に所定の平均粒子径の複数の負極用の活物質粒子を含む活物質層とを備えた負極電極を提供する。前記金属箔の表面は前記活物質層が位置する形成領域を含む。前記形成領域において前記金属箔はその表面に凹部を有し、前記活物質粒子の一部の活物質粒子は少なくとも部分的に前記凹部内に存在する活物質粒子である。前記少なくとも部分的に前記凹部内に存在する活物質粒子のうち、隣り合う活物質粒子の中心間の平均距離は前記平均粒子径の７０％以上９８％以下である。 A first aspect for achieving the above object provides a negative electrode including a metal foil and an active material layer including a plurality of negative electrode active material particles having a predetermined average particle diameter on the surface of the metal foil. The surface of the metal foil includes a formation region where the active material layer is located. In the formation region, the metal foil has a recess on its surface, and some of the active material particles of the active material particles are active material particles that are at least partially present in the recess. Of the active material particles present at least partially in the recess, the average distance between the centers of adjacent active material particles is 70% or more and 98% or less of the average particle diameter.
　第２の態様は、金属箔と、前記金属箔の表面に所定の平均粒子径の複数の負極用の活物質粒子を含む活物質層とを備えた負極電極を提供する。前記金属箔の表面は前記活物質層が位置する形成領域を含む。前記活物質粒子の一部の活物質粒子は少なくとも部分的に前記形成領域に埋没している活物質粒子である。前記少なくとも部分的に前記形成領域に埋没している活物質粒子のうち、隣り合う二つの活物質粒子の中心間の平均距離は前記平均粒子径の７０％以上かつ９８％以下である。 The second aspect provides a negative electrode including a metal foil and an active material layer including a plurality of negative electrode active material particles having a predetermined average particle diameter on the surface of the metal foil. The surface of the metal foil includes a formation region where the active material layer is located. Some of the active material particles are active material particles that are at least partially embedded in the formation region. Of the active material particles that are at least partially embedded in the formation region, the average distance between the centers of two adjacent active material particles is 70% or more and 98% or less of the average particle diameter.
　第３の態様は、活物質粒子を含む活物質層を金属箔の表面に形成した二以上の電極を、シート状をなすセパレータを間に挟んだ状態で積層又は捲回してなり、前記電極が層状の構造をなす電極組立体を有する蓄電装置を提供する。蓄電装置において、前記電極は、第１の態様または第２の態様の負極電極を含む。 In a third aspect, two or more electrodes in which an active material layer containing active material particles is formed on the surface of a metal foil are laminated or wound with a sheet-like separator sandwiched therebetween, Provided is a power storage device including an electrode assembly having a layered structure. In the power storage device, the electrode includes the negative electrode of the first aspect or the second aspect.
二次電池を模式的に示す斜視図。The perspective view which shows a secondary battery typically. 分解した電極組立体を模式的に示す斜視図。The perspective view which shows typically the decomposed | disassembled electrode assembly. 負極シートの断面を走査型電子顕微鏡で観察した状態を示す模式図。The schematic diagram which shows the state which observed the cross section of the negative electrode sheet with the scanning electron microscope. 平均粒子間距離と剥離強度との関係を示すグラフ。The graph which shows the relationship between the distance between average particle | grains, and peeling strength. 平均粒子間距離と放電容量維持率が８０％になる迄の充放電のサイクル数との間の関係を示すグラフ。The graph which shows the relationship between the distance between average particle | grains, and the cycle number of charging / discharging until a discharge capacity maintenance factor will be 80%. 別の実施形態における電極シートの模式図。The schematic diagram of the electrode sheet in another embodiment. また別の実施形態における二次電池を模式的に示す斜視図。The perspective view which shows typically the secondary battery in another embodiment. 更に別の実施形態における分解した電極組立体を模式的に示す斜視図。The perspective view which shows typically the disassembled electrode assembly in another embodiment.
　以下、負極電極、及び二次電池の一実施形態を図１～図５にしたがって説明する。
　蓄電装置としての二次電池１０は、例えば産業車両や乗用車両などの車両に搭載される。二次電池１０は、図１に示すように、全体として扁平な略直方体状のケース１１を有する。ケース１１は、有底筒状の本体部材１２と、本体部材１２の開口部１２ａを密閉する平板状の蓋部材１３とを有する。本体部材１２、及び蓋部材１３は、何れもステンレスやアルミニウムなどの金属製である。蓋部材１３には、正極端子１５、及び負極端子１６が固定され、外部に向かって延びている。 Hereinafter, one embodiment of a negative electrode and a secondary battery will be described with reference to FIGS.
The secondary battery 10 as a power storage device is mounted on a vehicle such as an industrial vehicle or a passenger vehicle. As shown in FIG. 1, the secondary battery 10 includes a case 11 having a substantially rectangular parallelepiped shape as a whole. The case 11 has a bottomed cylindrical main body member 12 and a flat lid member 13 that seals the opening 12 a of the main body member 12. Both the main body member 12 and the lid member 13 are made of metal such as stainless steel or aluminum. A positive electrode terminal 15 and a negative electrode terminal 16 are fixed to the lid member 13 and extend outward.
　ケース１１には、例えばリチウムイオン二次電池や、ニッケル水素二次電池というように、二次電池１０の種類に応じた電解液が充填されている。電解液としては、例えばプロピレンカーボネート（ＰＣ）、エチレンカーボネート（ＥＣ）、及びジメチルカーボネート（ＤＭＣ）から選ばれる１種以上の非水電解液を用いることができる。また、溶解させる電解質としては、ＬｉＰＦ６、ＬｉＢＦ４、及びＬｉＡｓＦ６などの有機溶媒に可溶なアルカリ金属塩を用いることができる。 The case 11 is filled with an electrolyte according to the type of the secondary battery 10 such as a lithium ion secondary battery or a nickel hydride secondary battery. As the electrolytic solution, for example, one or more nonaqueous electrolytic solutions selected from propylene carbonate (PC), ethylene carbonate (EC), and dimethyl carbonate (DMC) can be used. As the electrolyte to be dissolved, an alkali metal salt that is soluble in an organic solvent such as LiPF 6 , LiBF 4 , and LiAsF 6 can be used.
　また、ケース１１には、図示しない絶縁袋に覆われた電極組立体２５が収容されている。電極組立体２５は、正極電極としての正極シート２１、負極電極としての負極シート２２、及び正極シート２１と負極シート２２との間を絶縁するセパレータ２３を有する。電極組立体２５は、正極シート２１、及び負極シート２２を、間にセパレータ２３を介在させた状態で交互に層状に重なるように積層された積層型の電極組立体である。セパレータ２３は、ポリエチレンやポリプロピレンなどの絶縁性を有する樹脂材料製であり、微細な空孔構造を有する矩形の多孔性シートである。 The case 11 houses an electrode assembly 25 covered with an insulating bag (not shown). The electrode assembly 25 includes a positive electrode sheet 21 as a positive electrode, a negative electrode sheet 22 as a negative electrode, and a separator 23 that insulates between the positive electrode sheet 21 and the negative electrode sheet 22. The electrode assembly 25 is a stacked electrode assembly in which the positive electrode sheet 21 and the negative electrode sheet 22 are stacked so as to alternately overlap each other with a separator 23 interposed therebetween. The separator 23 is made of an insulating resin material such as polyethylene or polypropylene, and is a rectangular porous sheet having a fine pore structure.
　図２に示すように、正極シート２１及び負極シート２２の各々は、矩形シート状の金属箔２６を備えている。金属箔２６の厚さは、例えば１０μｍ以上５０μｍ以下であり、好ましくは１５μｍ以上２５μｍ以下である。金属箔２６は、例えばリチウムイオン二次電池や、ニッケル水素二次電池というように、二次電池１０の種類に応じた金属製である。金属箔２６に用いられる金属は、正極シート２１と、負極シート２２とによって異なる。本実施形態において、正極シート２１の金属箔２６はアルミニウム製であり、負極シート２２の金属箔２６は銅製である。 As shown in FIG. 2, each of the positive electrode sheet 21 and the negative electrode sheet 22 includes a rectangular sheet-like metal foil 26. The thickness of the metal foil 26 is, for example, 10 μm or more and 50 μm or less, and preferably 15 μm or more and 25 μm or less. The metal foil 26 is made of metal according to the type of the secondary battery 10 such as a lithium ion secondary battery or a nickel hydride secondary battery. The metal used for the metal foil 26 differs depending on the positive electrode sheet 21 and the negative electrode sheet 22. In the present embodiment, the metal foil 26 of the positive electrode sheet 21 is made of aluminum, and the metal foil 26 of the negative electrode sheet 22 is made of copper.
　各金属箔２６の表面２６ｃには、各金属箔２６の縁部２６ａに沿って延在する非形成領域２６ｂを除く全面に活物質層２７が設けられている。非形成領域２６ｂは、活物質層２７の形成されていない領域である。活物質層２７については、後に詳細に説明する。 On the surface 26c of each metal foil 26, an active material layer 27 is provided on the entire surface except for the non-formation region 26b extending along the edge 26a of each metal foil 26. The non-formation region 26b is a region where the active material layer 27 is not formed. The active material layer 27 will be described in detail later.
　各正極シート２１の縁部２６ａには、非形成領域２６ｂの一部である正極集電タブ２１ａが上方に延びている。また、各負極シート２２の縁部２６ａには、非形成領域２６ｂの一部である負極集電タブ２２ａが上方に延びている。 The positive electrode current collection tab 21a which is a part of the non-formation area | region 26b is extended to the edge part 26a of each positive electrode sheet 21 upwards. Moreover, the negative electrode current collection tab 22a which is a part of the non-formation area | region 26b is extended upwards at the edge part 26a of each negative electrode sheet 22. FIG.
　図１に示すように、電極組立体２５の縁部２５ａには、正極集電タブ群２８が上方に延びるように設けられている。正極集電タブ群２８は、層状に重なった複数の正極集電タブ２１ａからなる。また、電極組立体２５の縁部２５ａには、正極集電タブ群２８とは異なる部分に、負極集電タブ群２９が上方に延びるように設けられている。負極集電タブ群２９は、層状に重なった複数の負極集電タブ２２ａからなる。正極集電タブ群２８（正極集電タブ２１ａ）は、前述した正極端子１５と電気的に接続されている。また、負極集電タブ群２９（負極集電タブ２２ａ）は、負極端子１６と電気的に接続されている。 As shown in FIG. 1, a positive electrode current collecting tab group 28 is provided on the edge 25a of the electrode assembly 25 so as to extend upward. The positive electrode current collecting tab group 28 includes a plurality of positive electrode current collecting tabs 21a stacked in layers. Further, a negative electrode current collecting tab group 29 is provided on the edge 25 a of the electrode assembly 25 at a portion different from the positive electrode current collecting tab group 28 so as to extend upward. The negative electrode current collecting tab group 29 includes a plurality of negative electrode current collecting tabs 22a stacked in layers. The positive electrode current collecting tab group 28 (positive electrode current collecting tab 21a) is electrically connected to the positive electrode terminal 15 described above. Further, the negative electrode current collecting tab group 29 (negative electrode current collecting tab 22 a) is electrically connected to the negative electrode terminal 16.
　次に、正極シート２１及び負極シート２２において、各金属箔２６の表面２６ｃに設けられた活物質層２７について詳しく説明する。活物質層２７は、活物質粒子、バインダ、及び導電剤（導電助剤）を含んでいる。なお、導電剤はバインダに分散されている。 Next, the active material layer 27 provided on the surface 26 c of each metal foil 26 in the positive electrode sheet 21 and the negative electrode sheet 22 will be described in detail. The active material layer 27 includes active material particles, a binder, and a conductive agent (conductive aid). The conductive agent is dispersed in the binder.
　正極シート２１の活物質層２７に用いられる正極用の活物質は、例えばＬｉＣｏＯ２、Ｌｉ２ＭｎＯ２、及びＬｉＮｉ１／３Ｍｎ１／３Ｃｏ１／３Ｏ２である。正極シート２１の活物質層２７に用いられるバインダは、例えばポリビニリデンフルオライド（ＰＶＤＦ）やポリテトラフルオロエチレン（ＰＴＦＥ）である。正極シート２１の活物質層２７に用いられる導電剤は、例えばアセチレンブラック（ＡＢ）や、ケッチェンブラック（登録商標）（ＫＢ）である。 The active material for positive electrodes used for the active material layer 27 of the positive electrode sheet 21 is, for example, LiCoO 2 , Li 2 MnO 2 , and LiNi 1/3 Mn 1/3 Co 1/3 O 2 . The binder used for the active material layer 27 of the positive electrode sheet 21 is, for example, polyvinylidene fluoride (PVDF) or polytetrafluoroethylene (PTFE). The conductive agent used for the active material layer 27 of the positive electrode sheet 21 is, for example, acetylene black (AB) or ketjen black (registered trademark) (KB).
　負極シート２２の活物質層２７に用いられる負極用の活物質は、例えばＳｉＯｎ（０．１≦ｎ≦２）の組成式で示される酸化ケイ素であり、ＳｉＯ２（二酸化ケイ素）や、ＳｉＯ（一酸化ケイ素）である。負極シート２２の活物質層２７に用いられるバインダは、例えばＰＶＤＦやＰＴＦＥである。また、負極シート２２の活物質層２７に用いられる導電剤は、例えばＡＢや、ＫＢである。 The active material for a negative electrode used for the active material layer 27 of the negative electrode sheet 22 is, for example, silicon oxide represented by a composition formula of SiO n (0.1 ≦ n ≦ 2), such as SiO 2 (silicon dioxide), SiO 2 (Silicon monoxide). The binder used for the active material layer 27 of the negative electrode sheet 22 is, for example, PVDF or PTFE. Moreover, the electrically conductive agent used for the active material layer 27 of the negative electrode sheet 22 is AB or KB, for example.
　次に、図３にしたがって、負極シート２２の活物質層２７について詳しく説明する。
　負極シート２２の金属箔２６の表面２６ｃに形成された活物質層２７において、活物質粒子２７ａ同士は、バインダ２７ｂによって相互に結着されている。活物質粒子２７ａの平均粒子径は、例えば２μｍ以上１０μｍ以下であり、好ましくは４μｍ以上８μｍ以下である。なお本明細書における「平均粒子径」は、レーザ回折・散乱法によって求めた粒度分布における積算値５０％での粒子径を意味する。また、活物質粒子２７ａにおける個々の「粒子径」は、走査型電子顕微鏡（ＳＥＭ）にて観察される粒子径を意味する。 Next, the active material layer 27 of the negative electrode sheet 22 will be described in detail with reference to FIG.
In the active material layer 27 formed on the surface 26c of the metal foil 26 of the negative electrode sheet 22, the active material particles 27a are bound to each other by a binder 27b. The average particle diameter of the active material particles 27a is, for example, 2 μm or more and 10 μm or less, and preferably 4 μm or more and 8 μm or less. The “average particle size” in this specification means the particle size at an integrated value of 50% in the particle size distribution obtained by the laser diffraction / scattering method. Further, each “particle diameter” in the active material particles 27a means a particle diameter observed with a scanning electron microscope (SEM).
　負極シート２２の活物質層２７の形成領域２７ｃにおいて、金属箔２６の表面２６ｃの凹部２６ｄ内には、活物質粒子２７ａの一部が存在している。即ち、活物質層２７の形成領域２７ｃにおいて、活物質粒子２７ａのうち金属箔２６の表面２６ｃに近接する粒子の一部は、表面２６ｃの凹部２６ｄ内に存在するように埋没されている。更に換言すれば、金属箔２６において表面２６ｃを含む表面部には、活物質粒子２７ａが少なくとも部分的にめり込んでいる、即ち埋め込まれている。活物質粒子２７ａのうち埋没した活物質粒子２７ａを除く部分が金属箔２６の表面２６ｃよりも上方に位置している。そして、金属箔２６にめり込む活物質粒子２７ａの表面が凹部２６ｄを画定する面、例えば側面及び底面に接触又は近接している。 In the formation region 27c of the active material layer 27 of the negative electrode sheet 22, some of the active material particles 27a are present in the recesses 26d of the surface 26c of the metal foil 26. That is, in the formation region 27c of the active material layer 27, a part of the particles of the active material particles 27a adjacent to the surface 26c of the metal foil 26 is buried so as to exist in the recess 26d of the surface 26c. In other words, the active material particles 27a are at least partially embedded, that is, embedded in the surface portion of the metal foil 26 including the surface 26c. A portion of the active material particles 27 a excluding the buried active material particles 27 a is located above the surface 26 c of the metal foil 26. The surfaces of the active material particles 27a that are embedded in the metal foil 26 are in contact with or close to the surfaces that define the recesses 26d, for example, the side surfaces and the bottom surface.
　金属箔２６の凹部２６ｄ内に部分的に存在している活物質粒子２７ａのうち、隣り合う活物質粒子２７ａの中心Ｃ１から中心Ｃ２までの距離Ｌの平均（中心間の平均距離）は、活物質層２７に含まれる活物質粒子２７ａの平均粒子径を１００％とすると、好ましくは７０％以上９８％以下の距離、より好ましくは７２％以上９５％以下の距離とされている。 Of the active material particles 27a that are partially present in the recesses 26d of the metal foil 26, the average of the distances L from the center C1 to the center C2 of the adjacent active material particles 27a (the average distance between the centers) is the active material particle 27a. When the average particle diameter of the active material particles 27a included in the material layer 27 is 100%, the distance is preferably 70% to 98%, more preferably 72% to 95%.
　以下の説明では、平均粒子径に対して中心Ｃ１から中心Ｃ２までの距離Ｌの平均（中心間の平均距離）が占める割合を単に「平均粒子間距離」と定義する。また、本明細書において「活物質粒子２７ａの中心」とは、走査型電子顕微鏡にて観察した際において、金属箔２６の面方向に沿った方向、及び金属箔２６の面方向と直交する方向における中央を意味するものとする。 In the following description, the ratio of the average of the distance L from the center C1 to the center C2 (average distance between centers) with respect to the average particle diameter is simply defined as “average interparticle distance”. Further, in this specification, “the center of the active material particle 27a” means a direction along the surface direction of the metal foil 26 and a direction orthogonal to the surface direction of the metal foil 26 when observed with a scanning electron microscope. Means the center of
　負極シート２２の密度（電極密度）は、平均粒子間距離が９８％の場合に例えば１．０７ｇ／ｃｍ３となり、平均粒子間距離が７０％の場合に例えば１．０８ｇ／ｃｍ３となる。なお、負極シート２２の密度は、平均粒子間距離が７２％の場合に例えば１．２５ｇ／ｃｍ３となり、平均粒子間距離が９５％の場合に例えば１．０９ｇ／ｃｍ３となる。また、負極シート２２の活物質層２７において、金属箔２６の表面２６ｃの凹部２６ｄ内に部分的に存在している活物質粒子２７ａのうち、粒子径が平均粒子径以上である活物質粒子２７ａは、当該活物質粒子２７ａの粒子径の５０％以下の深さまで金属箔２６の凹部２６ｄに存在している。即ち、粒子径が平均粒子径以上である活物質粒子２７ａは、その粒子径の５０％を超えて金属箔２６に埋め込まれていない。なお、本実施形態の正極シート２１では、活物質層２７の形成領域２７ｃにおいて、活物質粒子２７ａが金属箔２６の表面２６ｃにめり込んでいない。 The density (electrode density) of the negative electrode sheet 22 is, for example, 1.07 g / cm 3 when the average interparticle distance is 98%, and is, for example, 1.08 g / cm 3 when the average interparticle distance is 70%. The density of the negative electrode sheet 22 is, for example, 1.25 g / cm 3 when the average interparticle distance is 72%, and is, for example, 1.09 g / cm 3 when the average interparticle distance is 95%. In the active material layer 27 of the negative electrode sheet 22, among the active material particles 27 a partially present in the recesses 26 d of the surface 26 c of the metal foil 26, the active material particles 27 a having a particle diameter equal to or larger than the average particle diameter. Is present in the recess 26d of the metal foil 26 to a depth of 50% or less of the particle diameter of the active material particles 27a. That is, the active material particles 27a having a particle diameter equal to or larger than the average particle diameter do not exceed 50% of the particle diameter and are not embedded in the metal foil 26. In the positive electrode sheet 21 of the present embodiment, the active material particles 27 a are not recessed into the surface 26 c of the metal foil 26 in the formation region 27 c of the active material layer 27.
　次に、正極シート２１及び負極シート２２を含む二次電池１０の製造方法について説明する。
　まず、活物質粒子２７ａと、導電剤と、バインダ２７ｂと、Ｎ－メチルピロリドン（ＮＭＰ）などの溶媒とを混合し、ペースト状の活物質合剤を得る調製工程が行われる。次に、調製工程で得られたペースト状の活物質合剤を、上記調製工程とは別の工程で得られた帯状（長尺のシート状）の金属箔２６の表面（両面）２６ｃに対して均一な厚さで塗布し、活物質層２７を形成する塗布工程が行われる。均一な厚さとは、例えば厚さ１８μｍの銅箔を含めて７０μｍ以上８０μｍ以下である。また塗布工程では、金属箔２６における幅方向の一辺（縁部）において、長さ方向の全体にわたり一定幅で活物質合剤を塗布しない非形成領域２６ｂが形成される。 Next, a method for manufacturing the secondary battery 10 including the positive electrode sheet 21 and the negative electrode sheet 22 will be described.
First, a preparation step is performed in which active material particles 27a, a conductive agent, a binder 27b, and a solvent such as N-methylpyrrolidone (NMP) are mixed to obtain a paste-like active material mixture. Next, the paste-like active material mixture obtained in the preparation step is applied to the surface (both sides) 26c of the strip-like (long sheet-like) metal foil 26 obtained in a step different from the preparation step. Then, a coating process is performed in which the active material layer 27 is formed by coating with a uniform thickness. The uniform thickness is, for example, 70 μm or more and 80 μm or less including a copper foil having a thickness of 18 μm. Further, in the coating step, a non-formation region 26b is formed on one side (edge) in the width direction of the metal foil 26 where the active material mixture is not coated with a constant width over the entire length direction.
　続けて、活物質層２７を形成した金属箔２６を、乾燥器（乾燥炉）に通過させ、活物質層２７に含まれる溶媒を除去する乾燥工程が行われる。次に、乾燥後の金属箔２６をロールプレス機に通過させることにより、活物質層２７を圧縮するとともに、高密度化及び平滑化させるプレス工程が行われる。ロールプレス機は、相互に平行に配置された一対の円柱状のローラ間に形成される隙間に、表面２６ｃに活物質層２７を形成した金属箔２６を通過させることにより、活物質層２７を圧縮、即ちプレスする。 Subsequently, a drying step is performed in which the metal foil 26 on which the active material layer 27 is formed is passed through a dryer (drying furnace) to remove the solvent contained in the active material layer 27. Next, by pressing the dried metal foil 26 through a roll press machine, a pressing process is performed in which the active material layer 27 is compressed and densified and smoothed. The roll press machine passes the metal foil 26 having the active material layer 27 formed on the surface 26c through a gap formed between a pair of cylindrical rollers arranged in parallel to each other, thereby causing the active material layer 27 to pass through. Compress, ie press.
　正極シート２１を製造する場合、このプレス工程では、ロールプレス機のローラ間で付与される線圧を、活物質層２７に含まれる活物質粒子２７ａが金属箔２６の表面２６ｃにめり込まない線圧に設定して行われる。このプレス工程を経て、帯状（長尺のシート状）の正極シート２１が得られる。 In the case of manufacturing the positive electrode sheet 21, in this pressing step, the active material particles 27 a included in the active material layer 27 do not sink into the surface 26 c of the metal foil 26 due to the linear pressure applied between the rollers of the roll press machine. This is done by setting the linear pressure. Through this pressing step, a belt-like (long sheet-like) positive electrode sheet 21 is obtained.
　これに対して、負極シート２２を製造する場合、プレス工程では、ロールプレス機のローラ間で付与される線圧を、活物質層２７に含まれる活物質粒子２７ａが金属箔２６の表面２６ｃ（表面部）にめり込む線圧に設定して行われる。また、プレス工程では、平均粒子間距離が活物質層２７に含まれる活物質粒子２７ａの平均粒子径の好ましくは７０％以上９８％以下、より好ましくは７２％以上９５％以下の距離となる線圧に設定される。さらに、プレス工程では、負極シート２２の活物質層２７において、金属箔２６の表面２６ｃの凹部２６ｄ内に部分的に存在している活物質粒子２７ａのうち、粒子径が平均粒子径以上である活物質粒子２７ａが、当該活物質粒子２７ａの粒子径の５０％以下の深さまで金属箔２６にめり込む線圧に設定される。即ち、負極シート２２の活物質粒子２７ａは、正極の活物質粒子２７ａに対して付与される線圧よりも大きな線圧でプレスされることによって、金属箔２６の表面に凹部２６ｄを形成しながら、その凹部２６ｄ内に部分的に存在するようにめり込む。このプレス工程を経て、帯状（長尺シート状）の負極シート２２が得られる。 On the other hand, when the negative electrode sheet 22 is manufactured, in the pressing step, the active material particles 27a included in the active material layer 27 are applied to the surface 26c ( This is performed by setting the linear pressure to be embedded in the surface portion. In the pressing step, the average particle distance is a line that is preferably 70% to 98%, more preferably 72% to 95% of the average particle diameter of the active material particles 27a included in the active material layer 27. Set to pressure. Furthermore, in the pressing step, in the active material layer 27 of the negative electrode sheet 22, the particle diameter of the active material particles 27 a partially present in the recesses 26 d of the surface 26 c of the metal foil 26 is equal to or greater than the average particle diameter. The active material particles 27a are set to a linear pressure that sinks into the metal foil 26 to a depth of 50% or less of the particle diameter of the active material particles 27a. That is, the active material particles 27a of the negative electrode sheet 22 are pressed with a linear pressure larger than the linear pressure applied to the positive electrode active material particles 27a, thereby forming the concave portions 26d on the surface of the metal foil 26. , So as to partially exist in the recess 26d. Through this pressing step, a strip-like (long sheet-like) negative electrode sheet 22 is obtained.
　次に、帯状（長尺シート状）の正極シート２１、及び負極シート２２をそれぞれ打ち抜き加工することにより、略矩形の正極シート２１、及び負極シート２２が形成される。次に、間にセパレータ２３を挟んだ状態で、正極シート２１及び負極シート２２を積層して電極組立体２５が形成される。これにより電極組立体２５が完成される。 Next, the substantially rectangular positive electrode sheet 21 and the negative electrode sheet 22 are formed by stamping the belt-like (long sheet-like) positive electrode sheet 21 and the negative electrode sheet 22 respectively. Next, the electrode assembly 25 is formed by laminating the positive electrode sheet 21 and the negative electrode sheet 22 with the separator 23 interposed therebetween. Thereby, the electrode assembly 25 is completed.
　続けて、電極組立体２５の正極集電タブ群２８（正極集電タブ２１ａ）には、正極端子１５が接合されて電気的に接続される。負極集電タブ群２９（負極集電タブ２２ａ）には、負極端子１６が接合されて電気的に接続される。続けて、電極組立体２５が前記絶縁袋で覆った状態で本体部材１２に収納される。この本体部材１２には、正極端子１５及び負極端子１６を上面から突出させつつ蓋部材１３が組み付けられる。そして、最終的に電解質（電解液）がケース１１内に充填されて二次電池１０が完成される。
＜実施例＞
　以下に実施例を挙げ、前記実施形態をさらに具体的に説明するが、本発明はこれらに限定されるものではない。
（負極シートの製作）
　市販の活物質粒子であるＳｉＯ粉末（シグマ・アルドリッチ・ジャパン株式会社製、平均粒子径＝５μｍ，タップ密度＝３．２ｇ／ｃｍ３）、ＫＢ、ポリアミドイミド樹脂（溶剤組成：ＮＭＰ／キシレン＝４／１、硬化残分３０．０％、硬化残分中のシリカ：２％（割合は全て重量比）、粘度８７００ｍＰａ・ｓ／２５℃）、及びＮＭＰを混合することにより、ペースト状の活物質合剤が得られる。活物質粒子、ＫＢ、及びバインダ（固形分）の配合比は、質量比で８０．７５：４．２５：１５であった。 Subsequently, the positive electrode terminal 15 is joined and electrically connected to the positive electrode current collecting tab group 28 (positive electrode current collecting tab 21a) of the electrode assembly 25. The negative electrode current collecting tab group 29 (the negative electrode current collecting tab 22a) is joined and electrically connected to the negative electrode terminal 16. Subsequently, the electrode assembly 25 is housed in the main body member 12 while being covered with the insulating bag. A lid member 13 is assembled to the main body member 12 with the positive electrode terminal 15 and the negative electrode terminal 16 protruding from the upper surface. Finally, an electrolyte (electrolytic solution) is filled in the case 11 to complete the secondary battery 10.
<Example>
Examples are given below to describe the above embodiments more specifically, but the present invention is not limited to these examples.
(Production of negative electrode sheet)
SiO powder (manufactured by Sigma-Aldrich Japan, average particle size = 5 μm, tap density = 3.2 g / cm 3 ), KB, polyamideimide resin (solvent composition: NMP / xylene = 4), which are commercially available active material particles / 1, cured residue 30.0%, silica in cured residue: 2% (all ratios are weight ratios, viscosity 8700 mPa · s / 25 ° C.), and NMP are mixed, and paste-like active material A mixture is obtained. The compounding ratio of the active material particles, KB, and binder (solid content) was 80.75: 4.25: 15 in terms of mass ratio.
　次に、得られたペースト状の活物質合剤が、帯状の銅箔の表面（両面）に対し塗布されて成形される。活物質合剤の目付量は７ｍｇ／ｃｍ２とした。このとき、活物質合剤と厚さ１８μｍの銅箔を含めた厚さは７６μｍである。 Next, the obtained paste-like active material mixture is applied to the surface (both sides) of the strip-shaped copper foil and molded. The basis weight of the active material mixture was 7 mg / cm 2 . At this time, the thickness including the active material mixture and the copper foil having a thickness of 18 μm is 76 μm.
　次に、活物質合剤を塗布した銅箔が乾燥器に通過され、溶媒を除去して乾燥される。続けて、乾燥後の銅箔をロールプレス機に通過させることにより、乾燥させた活物質層が圧縮される。そして、活物質層の厚さが１５μｍとなった。このとき、ロールプレス機のローラ間で付与される線圧を調節することにより、平均粒子間距離を異ならせた負極シートがそれぞれ得られた。
（走査型電子顕微鏡による観察）
　発明者らは、得られた負極シートを集束イオンビーム加工観察装置（日本電子社製，ＪＥＭ－９３１０ＦＩＢ）で切断するとともに、その断面を走査型電子顕微鏡（日立ハイテクノロジー社製，Ｓ－４８００）により観察した。その結果、制作した全ての負極シートについて、銅箔の表面に活物質粒子がめり込んでいることが観察された。即ち、銅箔の表面に凹部が形成され、活物質粒子の一部が当該凹部に存在することが観察された。
（目視による観察）
　また、発明者らは、製作された全ての負極シートについて、活物質層の形成領域（形成領域２７ｃ）と、非形成領域（非形成領域２６ｂ）との境界部において、銅箔に皺やクラックが発生しているか否かを観察した。 Next, the copper foil coated with the active material mixture is passed through a dryer to remove the solvent and dry. Subsequently, the dried active material layer is compressed by passing the dried copper foil through a roll press. And the thickness of the active material layer became 15 micrometers. At this time, negative electrode sheets with different average inter-particle distances were obtained by adjusting the linear pressure applied between the rollers of the roll press machine.
(Observation with a scanning electron microscope)
The inventors cut the obtained negative electrode sheet with a focused ion beam processing observation apparatus (JEM-9310FIB, manufactured by JEOL Ltd.), and a cross-section of the cross section with a scanning electron microscope (S-4800, manufactured by Hitachi High-Technologies Corporation). Was observed. As a result, it was observed that the active material particles were embedded in the surface of the copper foil for all the produced negative electrode sheets. That is, it was observed that a recess was formed on the surface of the copper foil and a part of the active material particles was present in the recess.
(Visual observation)
In addition, the inventors have found that all the manufactured negative electrode sheets have wrinkles and cracks in the copper foil at the boundary between the active material layer formation region (formation region 27c) and the non-formation region (non-formation region 26b). It was observed whether or not this occurred.
　その結果、銅箔の表面にめり込んでいる活物質粒子のうち、平均粒子径以上の径を有する活物質粒子が、当該活物質粒子の粒子径の５０％以下の深さまで銅箔にめり込んでいる、即ち銅箔の凹部に存在している試料については、前記境界部において、銅箔に皺やクラックが生じていなかった。 As a result, among the active material particles embedded in the surface of the copper foil, the active material particles having a diameter larger than the average particle diameter are embedded in the copper foil to a depth of 50% or less of the particle diameter of the active material particles. That is, for the sample present in the concave portion of the copper foil, no wrinkles or cracks occurred in the copper foil at the boundary portion.
　これに対して、銅箔の表面にめり込んでいる活物質粒子のうち、平均粒子径以上の径を有する活物質粒子が、当該活物質粒子の粒子径の５０％を超える深さまで銅箔にめり込んでいる試料については、前記境界部において、銅箔に皺などが生じていた。 On the other hand, among the active material particles embedded in the surface of the copper foil, the active material particles having a diameter equal to or larger than the average particle diameter are embedded in the copper foil to a depth exceeding 50% of the particle diameter of the active material particles. About the sample which is creased, the wrinkles etc. had arisen in the copper foil in the said boundary part.
　これは、活物質粒子の粒子径の５０％を超える深さまで活物質粒子をめり込む場合には、ロールプレス機のローラと弱く接触する活物質層の非形成領域と、当該非形成領域よりも強くローラと接する活物質層の形成領域との間で、銅箔の延伸量が異なる結果、前記境界部における銅箔に皺などが生じるものと考えられる。 This is because, when the active material particles are sunk to a depth exceeding 50% of the particle diameter of the active material particles, the active material layer non-formation region that is weakly in contact with the roller of the roll press machine is stronger than the non-formation region. It is considered that wrinkles and the like are generated in the copper foil at the boundary portion as a result of the difference in the amount of the copper foil stretched between the active material layer forming region in contact with the roller.
　したがって、負極シートの活物質層において、銅箔の表面にめり込んでいる活物質粒子のうち、平均粒子径以上の径を有する活物質粒子については、当該活物質粒子の粒子径の５０％を超えない深さまで銅箔にめり込ませることが好ましいことが確認された。
（剥離強度の測定）
　剥離強度は、粘着テープ及び粘着シート試験方法を用いて測定された。まず、製作した帯状の負極シートをそれぞれ打ち抜き加工することにより、長さ８０ｍｍ、幅２５ｍｍの帯状である試料がそれぞれ製作された。また剥離強度の測定方法では、スライド移動可能に支持された長方形の試験台の上に、市販の強力両面テープ（３Ｍ社製，ＹＨＢ　Ｙ－４９４５）を用い、試験台と試料の長手方向を一致させた状態で試料を貼り付けられる。試験台における試料の貼り付け面と直交する方向へ移動可能に支持された固定具に、試料における長手方向の端部が固定される。 Therefore, among the active material particles embedded in the surface of the copper foil in the active material layer of the negative electrode sheet, the active material particles having a diameter equal to or larger than the average particle diameter exceed 50% of the particle diameter of the active material particles. It has been confirmed that it is preferable to squeeze into the copper foil to a depth that does not.
(Measurement of peel strength)
Peel strength was measured using an adhesive tape and adhesive sheet test method. First, each of the manufactured strip-shaped negative electrode sheets was punched to prepare strip-shaped samples each having a length of 80 mm and a width of 25 mm. In the peel strength measurement method, a commercially available strong double-sided tape (manufactured by 3M, YHB Y-4945) is used on a rectangular test table supported so as to be slidable. The sample can be affixed in the state in which it is left. The end of the sample in the longitudinal direction is fixed to a fixture that is supported so as to be movable in a direction orthogonal to the sample attachment surface on the test table.
　そして、前記固定具に連結された荷重測定器（ミネビベア社製，ＬＴＳ－２００Ｎ－Ｓ２０）を試料から離間する方向へ２０ｍｍ／ｍｉｎの定速で移動させつつ、試験台から試料を剥離させる際の荷重が測定された。そして、測定された荷重のうち、剥離が開始された位置から１０ｍｍ～３０ｍｍの間における幅１ｃｍあたりの荷重の平均値が剥離強度として測定された。 Then, the load measuring device (manufactured by Minebea Co., Ltd., LTS-200N-S20) connected to the fixture is moved at a constant speed of 20 mm / min in a direction away from the sample, and the sample is peeled off from the test table The load was measured. Of the measured loads, the average value of the loads per 1 cm width between 10 mm and 30 mm from the position where peeling was started was measured as the peeling strength.
　平均粒子間距離を異ならせた負極シートの各試料について、剥離強度の測定結果を表１及び図４のグラフに示す。 The measurement results of peel strength are shown in the graphs of Table 1 and FIG. 4 for each sample of the negative electrode sheet with different average interparticle distances.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　表１及び図４に示すように、平均粒子間距離が６０％未満である場合には、平均粒子間距離が６０％以上である場合と比較して、剥離強度が低下することが確認された。これは、活物質粒子間に存在するバインダ量が少なく、活物質粒子と銅箔とを接着する強度が却って低下してしまうためと考えられる。また、平均粒子間距離が６０％以上９８％以下である場合においては、良好な剥離強度が発揮されることが確認された。 As shown in Table 1 and FIG. 4, when the average interparticle distance was less than 60%, it was confirmed that the peel strength was reduced as compared with the case where the average interparticle distance was 60% or more. . This is presumably because the amount of the binder existing between the active material particles is small, and the strength of bonding the active material particles and the copper foil is lowered instead. It was also confirmed that good peel strength was exhibited when the average interparticle distance was 60% or more and 98% or less.
　以上のことから、平均粒子間距離が６０％以上９８％以下である場合には、バインダによる接着に加えて、銅箔に対する活物質粒子のアンカー効果によって、活物質層と銅箔との剥離強度を好適に向上できることが確認された。なお、二次電池１０をフォークリフトなどの産業車両に搭載することを考慮した場合には、平均粒子間距離を７５％以上とし、２．６７Ｎ／ｃｍの剥離強度を確保することが好ましい。
（リチウムイオン二次電池の製作）
　上記の手順で作製した各負極シートを評価極として用い、リチウムイオン二次電池（ハーフセル）が作製された。対極として、金属リチウム箔（厚さ５００μｍ）を用いた。対極を直径φ１３ｍｍの円形に打ち抜き、評価極を直径φ１１ｍｍの円形に打ち抜き、セパレータ（ヘキストセラニーズ社製ガラスフィルターおよびｃｅｌｇａｒｄ２４００）を二つの電極の間に挟み込んで電極組立体が作製された。この電極組立体が電池ケース（宝泉株式会社製、ＣＲ２０３２コインセル）に収容された。また、電池ケースには、エチレンカーボネートとジエチルカーボネートとを体積比で１：１で混合した混合溶媒にＬｉＰＦ６を１Ｍ（モル）の濃度で溶解した非水電解質が注入された。そして電池ケースを密閉して、リチウム二次電池の各試料が得られた。
（サイクル特性の評価）
　サイクル特性を評価するために、各試料に対して充放電試験が行われた。充放電試験では、２５℃の温度環境のもと、まず金属Ｌｉ基準で放電終止電圧０．０１Ｖまで０．０５ｍＡの定電流で充電が行われた後、充電終止電圧２Ｖまで０．０５ｍＡの定電流で放電が行われた。初回の充放電試験後の最初の充放電試験を１サイクル目とし、５サイクル目まで同様の充放電が繰り返し行われた。引き続き、６～１０サイクル目は０．１ｍＡ、１１～１５サイクル目までは０．２ｍＡ、１６サイクル目以降は０．０５ｍＡとして充放電が繰り返し行われた。充放電の終止電圧は、いずれのサイクルも０．０１～２Ｖであった。 From the above, when the average inter-particle distance is 60% or more and 98% or less, the peel strength between the active material layer and the copper foil is obtained by the anchor effect of the active material particles to the copper foil in addition to the adhesion by the binder. It was confirmed that can be suitably improved. In consideration of mounting the secondary battery 10 on an industrial vehicle such as a forklift, it is preferable that the average interparticle distance is 75% or more and a peel strength of 2.67 N / cm is secured.
(Production of lithium ion secondary battery)
A lithium ion secondary battery (half cell) was produced using each negative electrode sheet produced by the above procedure as an evaluation electrode. A metal lithium foil (thickness: 500 μm) was used as the counter electrode. The counter electrode was punched into a circle with a diameter of 13 mm, the evaluation electrode was punched into a circle with a diameter of 11 mm, and a separator (Hoechst Celanese glass filter and celgard 2400) was sandwiched between the two electrodes to produce an electrode assembly. This electrode assembly was accommodated in a battery case (manufactured by Hosen Co., Ltd., CR2032 coin cell). In addition, a non-aqueous electrolyte in which LiPF 6 was dissolved at a concentration of 1 M (mol) in a mixed solvent in which ethylene carbonate and diethyl carbonate were mixed at a volume ratio of 1: 1 was injected into the battery case. And the battery case was sealed, and each sample of the lithium secondary battery was obtained.
(Evaluation of cycle characteristics)
In order to evaluate the cycle characteristics, a charge / discharge test was performed on each sample. In the charge / discharge test, under a temperature environment of 25 ° C., charging was first performed at a constant current of 0.05 mA up to a discharge end voltage of 0.01 V on a metal Li basis, and then a constant current of 0.05 mA up to a charge end voltage of 2 V. Discharge was performed with current. The first charge / discharge test after the first charge / discharge test was taken as the first cycle, and the same charge / discharge was repeated until the fifth cycle. Subsequently, charging and discharging were repeatedly performed at 0.1 mA for the 6th to 10th cycles, 0.2 mA for the 11th to 15th cycles, and 0.05 mA for the 16th and subsequent cycles. The final charge / discharge voltage was 0.01 to 2 V in all cycles.
　各サイクルで、電圧に対する活物質単位質量当たりの放電容量および充電容量が測定された。そして、各サイクルにおける放電容量維持率が算出された。なお、放電容量維持率は、Ｎサイクル目の放電容量を初回の放電容量で除した値の百分率（（Ｎサイクル目の放電容量）／（１サイクル目の放電容量）×１００）で求められる値である（Ｎは整数値）。 In each cycle, the discharge capacity and charge capacity per unit mass of active material with respect to voltage were measured. And the discharge capacity maintenance factor in each cycle was calculated. The discharge capacity retention ratio is a value obtained by dividing the N-th cycle discharge capacity by the initial discharge capacity ((N-cycle discharge capacity) / (first-cycle discharge capacity) × 100). (N is an integer value).
　平均粒子間距離を異ならせた負極シートを用いて製作したリチウムイオン二次電池の各試料について、放電容量維持率が８０％となる迄のサイクル数を測定した結果を図５に示す。 FIG. 5 shows the results of measuring the number of cycles until the discharge capacity retention rate reaches 80% for each sample of a lithium ion secondary battery manufactured using negative electrode sheets with different average interparticle distances.
　図５に示すように、平均粒子間距離が７０％以上９８％以下である場合には、優れたサイクル特性を示すことが確認された。また、平均粒子間距離７２％以上９５％以下である場合には、特に優れたサイクル特性を示すことが確認された。 As shown in FIG. 5, when the average interparticle distance is 70% or more and 98% or less, it was confirmed that excellent cycle characteristics were exhibited. Further, it was confirmed that particularly excellent cycle characteristics were exhibited when the average interparticle distance was 72% or more and 95% or less.
　ここで、平均粒子間距離が７０％未満である場合には、充電に伴う活物質粒子の膨張によって、凹部内に部分的に存在する活物質粒子同士が干渉して応力が発生し、活物質層が銅箔から剥離することに起因してサイクル特性が低下すると考えられる。 Here, when the average interparticle distance is less than 70%, the active material particles partially present in the recesses interfere with each other due to the expansion of the active material particles accompanying charging, and stress is generated. It is considered that the cycle characteristics deteriorate due to the layer peeling from the copper foil.
　これに対して、平均粒子間距離が９８％を超える場合には、９８％以下である場合と比較して、凹部内に部分的に存在する活物質粒子同士の離間距離が大きい。即ち、凹部内に部分的に存在する活物質粒子の数が少ない。そのため、充放電に伴って活物質層が銅箔から剥離し易く、これに起因してサイクル特性が低下すると考えられる。 On the other hand, when the average interparticle distance exceeds 98%, the separation distance between the active material particles partially existing in the recess is larger than when the average interparticle distance is 98% or less. That is, the number of active material particles partially present in the recess is small. Therefore, it is considered that the active material layer is easily peeled off from the copper foil with charge / discharge, and the cycle characteristics are deteriorated due to this.
　また、平均粒子間距離を７０％未満の距離とした場合には、活物質粒子同士が近接することから、活物質層に対する電解質の含浸に時間がかかる。したがって、二次電池１０の製造時間を短縮する観点からは、正極シートにおける平均粒子間距離を７０％以上とすることが好ましいといえる。 Also, when the average interparticle distance is less than 70%, the active material particles are close to each other, so that it takes time to impregnate the active material layer with the electrolyte. Therefore, from the viewpoint of shortening the manufacturing time of the secondary battery 10, it can be said that the average interparticle distance in the positive electrode sheet is preferably 70% or more.
　したがって、本実施形態によれば、以下のような効果を得ることができる。
　（１）負極シート２２において、金属箔２６の凹部２６ｄ内には活物質粒子２７ａの部分的に存在していることから、金属箔２６に対する活物質粒子２７ａのアンカー効果により活物質層２７が金属箔２６から剥離することを抑制できる。そして、凹部２６ｄに部分的に存在している活物質粒子２７ａのうち、隣り合う二つの活物質粒子２７ａの平均粒子間距離が７０％以上である場合には、７０％未満である場合と比較して、活物質粒子２７ａ同士が充電に伴う膨張に起因して相互に干渉することを抑制できる。その結果、活物質層２７が金属箔２６から剥離することを抑制できる。また、活物質粒子２７ａの平均粒子間距離が９８％以下である場合には、９８％を超える場合と比較して、活物質粒子２７ａの間隔を小さくしてアンカー効果を高め、これにより充放電に伴って活物質層２７が金属箔２６から剥離することを抑制できる。したがって、活物質層２７と金属箔２６とが剥離することを抑制できる。 Therefore, according to the present embodiment, the following effects can be obtained.
(1) In the negative electrode sheet 22, since the active material particles 27 a are partially present in the recesses 26 d of the metal foil 26, the active material layer 27 is made of metal by the anchor effect of the active material particles 27 a with respect to the metal foil 26. Separation from the foil 26 can be suppressed. And among the active material particles 27a partially existing in the recess 26d, when the average inter-particle distance between two adjacent active material particles 27a is 70% or more, it is compared with the case where it is less than 70%. And it can suppress that active material particle | grains 27a mutually interfere by the expansion | swelling accompanying charging. As a result, the active material layer 27 can be prevented from peeling from the metal foil 26. Further, when the average interparticle distance of the active material particles 27a is 98% or less, compared with the case where it exceeds 98%, the distance between the active material particles 27a is reduced to enhance the anchor effect, thereby charging and discharging. Accordingly, the active material layer 27 can be prevented from peeling from the metal foil 26. Therefore, it can suppress that the active material layer 27 and the metal foil 26 peel.
　（２）平均粒子径以上の径を有する活物質粒子２７ａが、その粒子径の５０％を超えて金属箔２６の凹部２６ｄ内に存在している場合には、金属箔２６の変形によって皺が生じる。しかしながら、本実施形態によれば、平均粒子径以上の径を有する活物質粒子２７ａは、当該活物質粒子２７ａの粒子径の５０％以下の深さまで凹部２６ｄ内に存在している。そのため、金属箔２６に皺が生じることを好適に抑制できる。 (2) When the active material particles 27 a having a diameter equal to or larger than the average particle diameter are present in the recess 26 d of the metal foil 26 exceeding 50% of the particle diameter, wrinkles are caused by the deformation of the metal foil 26. Arise. However, according to the present embodiment, the active material particles 27a having a diameter equal to or larger than the average particle diameter are present in the recess 26d to a depth of 50% or less of the particle diameter of the active material particles 27a. Therefore, wrinkles can be suitably suppressed from occurring in the metal foil 26.
　（３）負極シート２２の金属箔２６を銅箔とした場合、活物質層２７が銅製の金属箔２６から剥離することを抑制できる。
　（４）電極組立体２５では、間にセパレータ２３を挟んだ状態で正極シート２１及び負極シート２２を積層してなり、正極シート２１及び負極シート２２が層状をなしている。このため、正極シート２１及び負極シート２２が層状の構造をなす電極組立体２５において、負極シート２２の金属箔２６から活物質層２７が剥離してしまうことを抑制できる。 (3) When the metal foil 26 of the negative electrode sheet 22 is a copper foil, the active material layer 27 can be prevented from peeling from the copper metal foil 26.
(4) In the electrode assembly 25, the positive electrode sheet 21 and the negative electrode sheet 22 are laminated with the separator 23 interposed therebetween, and the positive electrode sheet 21 and the negative electrode sheet 22 are layered. For this reason, in the electrode assembly 25 in which the positive electrode sheet 21 and the negative electrode sheet 22 have a layered structure, it is possible to suppress the active material layer 27 from being separated from the metal foil 26 of the negative electrode sheet 22.
　（５）そして、電極組立体２５を構成する負極シート２２の金属箔２６から活物質層２７が剥離することを抑制できる結果、電極組立体２５を有する二次電池１０としての耐久性を向上させることができる。 (5) As a result of preventing the active material layer 27 from peeling from the metal foil 26 of the negative electrode sheet 22 constituting the electrode assembly 25, the durability of the secondary battery 10 having the electrode assembly 25 is improved. be able to.
　（６）負極シート２２において、凹部２６ｄ内に部分的に存在している活物質粒子２７ａのうち、隣り合う活物質粒子２７ａの平均粒子間距離を７２％以上とすることで、さらに二次電池１０としてのサイクル特性を向上できる。 (6) In the negative electrode sheet 22, among the active material particles 27a partially present in the recess 26d, the average inter-particle distance between the adjacent active material particles 27a is set to 72% or more to further increase the secondary battery. The cycle characteristic as 10 can be improved.
　（７）負極シート２２において、凹部２６ｄ内に部分的に存在している活物質粒子２７ａのうち、隣り合う活物質粒子２７ａの平均粒子間距離を９５％以下とすることで、さらに二次電池１０としてのサイクル特性を向上できる。 (7) In the negative electrode sheet 22, among the active material particles 27a partially present in the recess 26d, the average inter-particle distance between the adjacent active material particles 27a is set to 95% or less to further increase the secondary battery. The cycle characteristic as 10 can be improved.
　（８）負極シート２２において、凹部２６ｄ内に部分的に存在している活物質粒子２７ａのうち、隣り合う活物質粒子２７ａの平均粒子間距離を７５％以上とすることで、活物質層２７に電解質（電解液）を含浸させるのに要する時間が長くなることを抑制できる。 (8) In the negative electrode sheet 22, among the active material particles 27a partially present in the recess 26d, the average inter-particle distance between adjacent active material particles 27a is 75% or more, so that the active material layer 27 It is possible to prevent the time required for impregnating the electrolyte (electrolyte solution) into a long time.
　（９）負極シート２２において、凹部２６ｄ内に部分的に存在している活物質粒子２７ａのうち、隣り合う活物質粒子２７ａの平均粒子間距離を７５％以上とすることで、二次電池１０が産業車両へ搭載された場合、大きな振動が二次電池１０に加わる条件下でも活物質層２７が金属箔２６から剥離することを抑制できる。 (9) In the negative electrode sheet 22, among the active material particles 27a partially present in the recess 26d, the average inter-particle distance between the adjacent active material particles 27a is set to 75% or more, so that the secondary battery 10 Is mounted on an industrial vehicle, it is possible to suppress the active material layer 27 from being peeled off from the metal foil 26 even under a condition in which large vibrations are applied to the secondary battery 10.
　実施形態は上記のように限定されるものではなく、例えば以下のように具体化してもよい。
　○　図６に示すように、負極シート２２における金属箔２６の表面２６ｃにおいて活物質層２７の形成されていない非形成領域２６ｂには、金属箔２６と同一金属である補助金属箔３５が接合されていてもよい。金属箔２６と補助金属箔３５との接合は、例えば抵抗溶接の一種であるシーム溶接により行うとよい。この場合、補助金属箔３５の厚さは、活物質層２７と略同一厚さに設定するとよい。これによれば、活物質層２７の形成されていない非形成領域２６ｂに補助金属箔３５が接合されていることから、例えばプレスにより活物質層２７の形成領域２７ｃを加圧することで、凹部２６ｄを形成しながら当該凹部２６ｄ内に部分的に活物質粒子２７ａを存在させる場合に、金属箔２６に皺が生じることを抑制できる。 The embodiment is not limited as described above, and may be embodied as follows, for example.
As shown in FIG. 6, the auxiliary metal foil 35, which is the same metal as the metal foil 26, is joined to the non-formation region 26 b where the active material layer 27 is not formed on the surface 26 c of the metal foil 26 in the negative electrode sheet 22. It may be. The metal foil 26 and the auxiliary metal foil 35 may be joined by, for example, seam welding, which is a type of resistance welding. In this case, the thickness of the auxiliary metal foil 35 is preferably set to be substantially the same as that of the active material layer 27. According to this, since the auxiliary metal foil 35 is joined to the non-formation region 26b where the active material layer 27 is not formed, the depression 26d is formed by pressurizing the formation region 27c of the active material layer 27 by, for example, pressing. When the active material particles 27a are partially present in the recesses 26d while forming the metal foil 26, the occurrence of wrinkles in the metal foil 26 can be suppressed.
　○　図６において二点鎖線で示すように、補助金属箔３５と金属箔２６とは、補助金属箔３５及び金属箔２６を形成する金属よりも電気抵抗が高い金属からなるシート３５ａを間に挟んだ状態で接合されていてもよい。これによれば、補助金属箔３５と金属箔２６とを抵抗溶接しやすくできる。 ○ As shown by a two-dot chain line in FIG. 6, the auxiliary metal foil 35 and the metal foil 26 sandwich a sheet 35 a made of a metal having higher electrical resistance than the metal forming the auxiliary metal foil 35 and the metal foil 26. It may be joined in a state. According to this, resistance welding of the auxiliary metal foil 35 and the metal foil 26 can be facilitated.
　○　図６に示すように、活物質層２７は金属箔２６の片面にのみ形成されていてもよい。
　○　図７及び図８に示すように、電極組立体２５は、正極シート２１、負極シート２２、及びセパレータ２３を帯状（長尺のシート状）であってもよい。セパレータ２３を間に挟んだ状態で、正極シート２１及び負極シート２２を渦まき状に捲回し、正極シート２１及び負極シート２２が層状の構造（積層構造）をなすように電極組立体２５が形成されてもよい。この場合、正極シート２１において幅方向（横方向）の一方の縁部（図７の左縁部）には、正極シート２１の長さ方向に沿って延びる非形成領域２６ｂが形成され、当該非形成領域２６ｂが正極集電タブ２１ａとなる。これに対して、負極シート２２において幅方向の他方の縁部（図７の右縁部）には、負極シート２２の長さ方向に沿って延びる非形成領域２６ｂが形成され、当該非形成領域２６ｂが負極集電タブ２２ａとなる。そして、正極シート２１及び負極シート２２を捲回することで、電極組立体２５の左縁部に正極集電タブ２１ａが層状の構造をなす正極集電タブ群２８が設けられる一方で、電極組立体２５の右縁部に負極集電タブ２２ａが層状の構造をなす負極集電タブ群２９が設けられてもよい。 As shown in FIG. 6, the active material layer 27 may be formed only on one side of the metal foil 26.
As shown in FIGS. 7 and 8, the electrode assembly 25 may have a positive electrode sheet 21, a negative electrode sheet 22, and a separator 23 in a strip shape (long sheet shape). The positive electrode sheet 21 and the negative electrode sheet 22 are wound in a spiral shape with the separator 23 sandwiched therebetween, and the electrode assembly 25 is formed so that the positive electrode sheet 21 and the negative electrode sheet 22 form a layered structure (laminated structure). May be. In this case, in the positive electrode sheet 21, a non-formation region 26b extending along the length direction of the positive electrode sheet 21 is formed at one edge (left edge in FIG. 7) in the width direction (lateral direction). The formation region 26b becomes the positive electrode current collecting tab 21a. In contrast, in the negative electrode sheet 22, a non-formation region 26 b extending along the length direction of the negative electrode sheet 22 is formed on the other edge portion in the width direction (the right edge portion in FIG. 7). 26b becomes the negative electrode current collection tab 22a. Then, by winding the positive electrode sheet 21 and the negative electrode sheet 22, the positive electrode current collecting tab group 28 in which the positive electrode current collecting tab 21 a has a layered structure is provided on the left edge portion of the electrode assembly 25. A negative electrode current collecting tab group 29 in which the negative electrode current collecting tab 22a has a layered structure may be provided on the right edge of the solid body 25.
　○　正極シート２１、及び負極シート２２の形状を変更してもよい。
　○　正極シート２１の活物質層２７において、活物質粒子２７ａは金属箔２６の凹部２６ｄ内に部分的にめり込んで存在していてもよい。 The shape of the positive electrode sheet 21 and the negative electrode sheet 22 may be changed.
In the active material layer 27 of the positive electrode sheet 21, the active material particles 27 a may exist by being partially embedded in the recesses 26 d of the metal foil 26.
　○　電極組立体２５は、セパレータ２３を間に挟んだ状態で正極シート２１及び負極シート２２を蛇腹状に折り曲げて積層されてもよい。
　○　正極シート２１に用いる金属箔２６は、ニッケルやステンレスなど、異なる金属から形成されていてもよい。同様に負極シート２２についても、金属箔２６の金属を変更してもよい。 The electrode assembly 25 may be laminated by folding the positive electrode sheet 21 and the negative electrode sheet 22 into a bellows shape with the separator 23 interposed therebetween.
(Circle) the metal foil 26 used for the positive electrode sheet 21 may be formed from different metals, such as nickel and stainless steel. Similarly, for the negative electrode sheet 22, the metal of the metal foil 26 may be changed.
　○　金属箔２６の表面２６ｃにおける凹部２６ｄ内に存在している活物質粒子２７ａのうち、平均粒子径以上の径を有する活物質粒子２７ａは、当該活物質粒子２７ａの粒子径の５０％以上の深さまで凹部２６ｄに存在していてもよい、即ち金属箔２６にめり込んでいてもよい。但し、金属箔２６の皺の発生を抑制する観点からは上記実施形態のように構成することが好ましい。 ○ Among the active material particles 27a existing in the recesses 26d on the surface 26c of the metal foil 26, the active material particles 27a having a diameter equal to or larger than the average particle diameter are 50% or more of the particle diameter of the active material particles 27a. It may exist in the recess 26d to the depth, that is, it may be embedded in the metal foil 26. However, from the viewpoint of suppressing generation of wrinkles of the metal foil 26, it is preferable to configure as in the above embodiment.
　○　電極組立体２５を構成する正極シート２１、及び負極シート２２の数は適宜変更してもよい。例えば、正極シート２１、及び負極シート２２をそれぞれ１つ備えた電極組立体２５としてもよい。 ○ The number of the positive electrode sheet 21 and the negative electrode sheet 22 constituting the electrode assembly 25 may be appropriately changed. For example, the electrode assembly 25 may include one positive electrode sheet 21 and one negative electrode sheet 22.
　○　ケース１１の形状は、円柱状や、横方向に扁平な楕円柱状であってもよい。
　○　上記実施形態の二次電池１０を車両（例えば産業車両や乗用車両）に搭載し、車両に装備された発電機により充電する一方で、二次電池１０から供給する電力によりエアコン用のコンプレッサや、車輪を駆動するための電動モータ、或いはカーナビゲーションシステムなどの電装品を駆動してもよい。これによれば、金属箔２６から活物質層２７が剥離することを抑制し、二次電池１０としての耐久性を向上できる。したがって、車両において二次電池１０の交換サイクルが短くなることを抑制できる。 The shape of the case 11 may be a columnar shape or an elliptical column shape that is flat in the horizontal direction.
○ While the secondary battery 10 of the above embodiment is mounted on a vehicle (for example, an industrial vehicle or a passenger vehicle) and is charged by a generator installed in the vehicle, a compressor for an air conditioner is supplied by electric power supplied from the secondary battery 10 Alternatively, an electric motor for driving the wheels or an electrical component such as a car navigation system may be driven. According to this, it can suppress that the active material layer 27 peels from the metal foil 26, and can improve the durability as the secondary battery 10. Therefore, it can suppress that the replacement cycle of the secondary battery 10 becomes short in a vehicle.
　○　本発明は、蓄電装置としての電気二重層キャパシタに具体化してもよい。 ○ The present invention may be embodied in an electric double layer capacitor as a power storage device.

Claims (8)

  1. 　金属箔と、
    　前記金属箔の表面に所定の平均粒子径の複数の負極用の活物質粒子を含む活物質層とを備え、
    　前記金属箔の表面は前記活物質層が位置する形成領域を含み、前記形成領域において前記金属箔はその表面に凹部を有し、前記活物質粒子の一部の活物質粒子は少なくとも部分的に前記凹部内に存在する活物質粒子であり、
    　前記少なくとも部分的に前記凹部内に存在する活物質粒子のうち、隣り合う活物質粒子の中心間の平均距離は前記平均粒子径の７０％以上９８％以下である、負極電極。     Metal foil,
    An active material layer including a plurality of negative electrode active material particles having a predetermined average particle diameter on the surface of the metal foil,
    The surface of the metal foil includes a formation region where the active material layer is located. In the formation region, the metal foil has a recess in the surface, and some of the active material particles are at least partially Active material particles present in the recess,
    The negative electrode whose average distance between the centers of adjacent active material particles among the active material particles present at least partially in the recess is 70% or more and 98% or less of the average particle diameter.
  2. 　前記少なくとも部分的に前記凹部に存在する活物質粒子のうち、前記平均粒子径以上の粒子径の活物質粒子は、当該活物質粒子の粒子径の５０％以下の深さまで埋没された状態で前記凹部に存在する請求項１に記載の負極電極。 Of the active material particles present at least partially in the recess, the active material particles having a particle diameter equal to or greater than the average particle diameter are embedded in a state where the active material particles are buried to a depth of 50% or less of the particle diameter of the active material particles. The negative electrode according to claim 1, which exists in the recess.
  3. 　金属箔と、
    　前記金属箔の表面に所定の平均粒子径の複数の負極用の活物質粒子を含む活物質層とを備え、
    　前記金属箔の表面は前記活物質層が位置する形成領域を含み、
    　前記活物質粒子の一部の活物質粒子は少なくとも部分的に前記形成領域に埋没している活物質粒子であり、
    　前記少なくとも部分的に前記形成領域に埋没している活物質粒子のうち、隣り合う二つの活物質粒子の中心間の平均距離は前記平均粒子径の７０％以上かつ９８％以下である、負極電極。     Metal foil,
    An active material layer including a plurality of negative electrode active material particles having a predetermined average particle diameter on the surface of the metal foil,
    The surface of the metal foil includes a formation region where the active material layer is located,
    Some of the active material particles of the active material particles are active material particles that are at least partially embedded in the formation region,
    Of the active material particles that are at least partially embedded in the formation region, the average distance between the centers of two adjacent active material particles is 70% or more and 98% or less of the average particle diameter. .
  4. 　前記少なくとも部分的に前記形成領域に埋没している活物質粒子のうち、前記平均粒子径以上の粒子径の活物質粒子は、当該活物質粒子の粒子径の５０％以下の深さまで埋没されている、請求項３に記載の電極。 Of the active material particles that are at least partially embedded in the formation region, the active material particles having a particle diameter greater than or equal to the average particle diameter are embedded to a depth of 50% or less of the particle diameter of the active material particles. The electrode according to claim 3.
  5. 　前記金属箔の表面は前記活物質層が位置しない非形成領域を含み、前記非形成領域には、前記金属箔と同一金属からなる補助金属箔が接合されている、請求項１～４の何れか一項に記載の負極電極。 The surface of the metal foil includes a non-formation region where the active material layer is not located, and an auxiliary metal foil made of the same metal as the metal foil is joined to the non-formation region. The negative electrode according to claim 1.
  6. 　前記金属箔は銅からなる、請求項１～５のいずれか１項に記載の負極電極。 The negative electrode according to any one of claims 1 to 5, wherein the metal foil is made of copper.
  7. 　活物質粒子を含む活物質層を金属箔の表面に形成した二以上の電極を、シート状をなすセパレータを間に挟んだ状態で積層又は捲回してなり、前記電極が層状の構造をなす電極組立体を有する蓄電装置において、
    　前記電極は、請求項６に記載の負極電極を含む、蓄電装置。     An electrode in which two or more electrodes each having an active material layer containing active material particles formed on the surface of a metal foil are laminated or wound with a sheet-like separator interposed therebetween, and the electrode has a layered structure. In a power storage device having an assembly,
    The said electrode is an electrical storage apparatus containing the negative electrode of Claim 6.
  8. 　請求項７に記載の蓄電装置を搭載した車両。 A vehicle equipped with the power storage device according to claim 7.
PCT/JP2014/069279 2013-08-21 2014-07-22 Negative electrode, electricity storage device and vehicle WO2015025663A1 (en)

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